1. Field of the Invention
The present invention relates to hot fill processing systems for liquid food products. More specifically, the present invention relates to a product recovery system for a hot fill pasteurization system.
2. Description of the Related Art
Liquid food products are packaged in a variety of containers such as polyethylene terephthlate ("PET") bottles, blow molded high density polyethylene ("HDPE") jugs, gable-top cartons, glass bottles, aluminum cans, pouches and parallelepiped containers (e.g. the TETRA BRIK.RTM. package). Liquid food products include fruit juices, sports drinks, tea, milk, soft drinks, and the like. It has become commonplace to have more shelf stable products and extended shelf life ("ESL") products. A shelf stable product is defined as a product that may be stored without refrigeration for up to three months while an ESL product is defined as one that may be stored with refrigeration for up to four months. The popularity of these products with retailers is due to the extended amount of time that the product may be "marketed" to the consuming public without spoilage.
In order to obtain ESL and shelf stable products, the liquid food product most be processed in a manner that renders the product essentially free of micro-organisms and microbial growth. Several methods are utilized to process products in this manner. One such process is a hot fill pasteurization process.
Basically, a hot fill pasteurization process is a continuous flow through processing system which heat treats the product to kill micro-organisms . The product is then directed to a container filling machine which fills the product into a container at an elevated temperature (hot fill). The heat treatment and the hot fill render the product shelf stable.
In a typical hot fill pasteurization system, a product such as fruit juice is pumped from an external storage tank to a primary balance tank as needed to maintain a constant level in the primary balance tank. The product is continually pumped from the primary balance tank through a product heater, then through a holding loop, then through a product cooler and to a filler feed tank. The heater typically uses hot water to heat to heat the product to an elevated temperature, usually 87.degree. C. to 119.degree. C. (190.degree. F. to 245.degree. F.). The holding loop maintains the product at this elevated temperature for a predetermined time period necessary to kill the micro-organisms. The predetermined time period will vary depending on the product. The cooler uses cold water to cool the temperature of the product to a hot fill temperature. For example, for a PET bottle, the hot fill temperature is 85.degree. C. (185.degree. F.) which is just below the softening temperature of the PET bottle. Hot filling containers maximizes shelf life by killing organisms on the container surface, and also assists in vacuum sealing of the container.
At the filler feed tank, the product is pumped to a filler where most of the product is filled into containers. A portion of the product overflows from the filler into a filler overflow tank or return tank. The overflow product from the filler is approximately 5% to 25% of the total product fed to the filler when the filler is filling containers and 100% when containers are not being conveyed through the filler. The latter scenario occurs during priming of the processing system or during shut-down of the system. Overflow product from the filler overflow tank is pumped to the main balance tank where it joins fresh product feeding into the system. In this manner the overflow product is processed through the entire cycle again.
Once a product batch is completed, the product remaining in the system is rendered excess product. This remaining product is either in the overflow tank, in the primary balance tank or in the sterilization portion of the system (the heater and cooler). Current practice is to dispose of the excess product or to transfer it to a separate tank where the products value is greatly diminished. Depending on the product and processing system, this excess product could account for 25% to 100% of the system hold-up volume.